Method for extracting and fractionating fats with solvent, using at least a hydrofluroether

ABSTRACT

The invention concerns a method for extracting and fractionating fats contained in a raw material, characterized in that it comprises at least a step which consists in using an extraction solvent consisting of at least a hydrofluoroether of general formula (I): C n F 2n+1 OC m H 2m+1 , wherein: n ranges between 3 and 6 and m ranges between 1 and 5 and at least a separation step enabling to obtain a raw extract of fats rich in unsaponifiable substances and optionally, in free fatty acids and a insoluble extraction fraction.

CROSS-REFERENCE TO RELATED APPLICATION

This Application is a Section 371 National Stage Application ofInternational Application No. PCT/FR00/03658 filed Dec. 21, 2000 andpublished as WO 01/46354 on Jun. 28, 2001, not in English.

1. Field of the Invention

The invention concerns the field of extraction chemistry.

2. Background of the Invention

More precisely, the present invention relates to the extraction of fattymaterial from natural raw materials.

The fatty materials, principally those of plant origin, are ingredientswidely used by the food, cosmetic and pharmaceutical industries.

However, these fatty materials may rarely be used in the crude state andmust generally be subjected to a refining in order to remove one or moreundesirable components, the nature of which depends on the applicationsprovided for the refined product.

Thus, the cosmetic and pharmaceutical industries use fatty materialsenriched in unsaponifiable materials that is according to the Frenchstandard NFT 60-205-1 in substances which, after saponification of thefatty material by potassium hydroxide and extraction by a specifiedsolvent, are not volatile under specified conditions. The fattymaterials enriched in unsaponifiables have particularly high contents ofhydrocarbons, heavy alcohols (aliphatic or terpene), sterols andtocopherols and are obtained after removal of a part of thetriglycerides which are the predominant components of the crude fattymaterial.

Among the numerous extraction and fractionation methods of fattymaterials proposed in the state of the technique, solvent extraction isa very widespread technique which is available according to numeroustechnological variants.

Thus, the patent application FR 2 702 773 proposes a method forpreparation of fractions of plant fatty materials enriched inunsaponifiable materials. In this method, the plant fatty material istreated with acetone so as to recover, on the one hand a fractioninsoluble with heat, rich in unsaponifiable and on the other hand, asoluble fraction subjected later to a cold crystallization step. Afterfiltration of the precipitate, the filtrate is evaporated to dryness.The evaporation residue also forms a fraction enriched inunsaponifiable. On the other hand, the precipitate is enriched intriglycerides.

It will be noted that, according to the raw material from which they areextracted, the plant fatty materials have different compositions,qualitatively and quantitatively. These differences may justify the useof solvents different from acetone (for example, hexane or ethanol) asmuch at the hot extraction step as at the cold precipitation step.

The principal drawback of the extraction and fractionation methods bysolvent results from the use of organic solvents (alkanes, ketones,esters, alcohols, ethers, chlorinated solvents) which subject theextract obtained to regulatory constraints related to the contents ofresidual solvents. In fact, whatever their nature, these organicsolvents are either harmful or toxic. This harmfulness and this toxicityare demonstrated at generally low contents of residual solvents in theextracts obtained. In order to eliminate the health-related risks,therefore it is necessary to use desolvation methods which presentseveral drawbacks. In fact, beside the additional cost that they incur,these desolvation methods, according to the operating conditionsapplied, may have a negative effect on the quality of the extracts thustreated.

These constraints also concern the risks of solvent discharge in liquidor gaseous form in the natural medium. Finally, with the exception ofthe alkanes, the traditional extraction solvents present the drawback ofnot having total chemical inertness, risking leading to denaturation ofthe products obtained, according to the extraction conditions or storageof the extracts.

BRIEF SUMMARY OF THE INVENTION

The principal objective of the present invention is to propose anextraction and fractionation method of fatty material by a solvent thatdoes not present such drawbacks.

Such a method according to the invention is characterized in that itconsists of at least one step using an extraction solvent formed by atleast a hydrofluoroether (abbreviated HFE) with general formula (I):

C_(n)F_(2n+1)OC_(m)H_(2m+1)

in which n is between 3 and 6 and m is between 1 and 5 and at least oneseparation step leading to obtaining on the one hand a crude extract offatty material rich in unsaponifiable materials and, possibly, in freefatty acids and on the other hand, to an extraction insoluble fraction.

These hydrofluoroethers, by comparison with conventional solvents,present the following advantages by comparison with conventionalsolvents.

They are non-flammable and because of this, do not require the use ofspecific production and protection equipment. This characteristic isvery particularly interesting from the angle of production on industrialscale since it has a direct effect on the cost of the finished products;

They do not present a risk for the ecosystem and are in conformity withthe strictest environmental regulations (zero potential for destructionof the ozone layer and very low contribution to the greenhouse effect);

They are chemically inert, odorless, colorless and flavorless.Therefore, they do not have any negative effect on the properties ofextracts or formulations which contain them or which they are used toprepare.

Even at high doses, they are nontoxic by inhalation, absorption orrepeated contact;

Finally, they have a low thermal capacity and latent heat ofvaporization compared with those of organic solvents currently used inextraction; therefore, the method according to the invention is not verycostly in energy.

Preferentially, said hydrofluoroether is chosen frommethoxynonafluorobutane with formula C₄F₉—O—CH₃ (also designated in thechemical industry by the name HFE7100) and ethoxynonafluorobutaneC₄F₉—O—C₂H₅ (also designated in the chemical industry by the nameHFE-7200).

These compounds present the advantage of having boiling points of 60°C., for methoxynonafluorobutane and 78° C. for ethoxynonafluorobutanewhich allow their use in traditional solid-liquid or liquid-liquidextraction equipment without notable modification of these latter.Moreover, these hydrofluoroethers may be used in the extraction methodsresorting to new technologies such as microwaves or ultrasound.

It will be noted that the use of hydrofluoroethers as extraction agentshas already been described in the patent PCT FR98/02546. This documentdiscloses the solubilizing nature of the HFE for the preparation ofplant extracts, however in contrast to the present invention, withoutbringing out the particularly selective nature of these HFE with respectto the particular classes of chemical compounds that are lipid fractionsrich in unsaponifiable materials.

On the other hand, the present invention shows that the HFE, with goodselectivity are likely to extract such lipid fractions rich inunsaponifiable materials.

It will be noted that this selectivity is not total since the HFE withformula (I) coextract the lipid substances not belonging to the categoryof unsaponifiable materials, in particular triglycerides and free fattyacids. The coextraction of free fatty acids in certain cases forms anadditional advantage of the method, particularly in the case of matrixescontaining free fatty acids of pharmaceutical, cosmetic or nutritionalinterest.

According to a preferential variant of the invention, it is possible toenrich again the crude extract of obtained fatty material, rich inunsaponifiable substances and free fatty acids, by a precipitation stepselective for coextracted triglycerides consisting of cooling said crudeextract to a temperature lower than the extraction temperature.

Therefore, the method according to the invention makes it possible tofractionate the fatty material into fractions enriched in unsaponifiablematerials and into free fatty acids and into fractions enriched intriglycerides.

The fractions obtained may be as well suited for cosmetic applicationsas for pharmaceutical or food applications.

According to a preferential variant of the invention, the methodcomprises an additional step consisting of decanting said filtrate thenevaporating the latter so as to recover a soluble extract very enrichedin unsaponifiable substances and in free fatty acids.

According to another advantageous aspect of the method according to theinvention, said insoluble fraction is recycled to the beginning of themethod.

It will be noted that the method according to the invention could beused in the presence of at least one cosolvent chosen from alkanes,ketones, alcohols, alkyl ethers, carboxylic acids, esters, amides,halogenated hydrocarbons, acetals.

The invention as well as the different advantages that it presents willnow be more easily understood as a result of the description thatfollows with examples that are nonlimiting for its achievement.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS EXAMPLE 1 Fractionation ofShea Butter and a Fraction Enriched in Triglycerides and a FractionEnriched in unsaponifiable

Shea butter (20 g) measured at 7-8% unsaponifiables, shaken at 40° C.for 1 h 30 min in 2 liters of ethoxynonafluorobutane (C₄F₉—O—C₂H₅).After stopping the shaking, the suspension is left to decant for 20 min.The fluorinated phase is then separated from the extraction insolublethen cooled to 8° C. After 2 h of decanting, the cooled suspension isfiltered on a screen with mesh of 10 μm. The clear filtrate isevaporated to dryness.

The qualitative analysis of the fractions is carried out by thin layerchromatography (silica) with the aid of a hexane/ethyl ether/acetic acideluant in proportions by volume of 90/10/1. Deposits correspond to 6 μLof hexane solutions at 20 mg/mL. The plates are dried then visualized byethanol with 5% sulphuric acid (drying at 110° C.). The results showclearly that the P_(E) fraction (precipitated extract) is formed nearlyexclusively of triglycerides. On the other hand, the SE fraction(soluble extract) is very enriched in unsaponifiable substances(karitene, sterols and fatty alcohols especially). These results aresummarized in Table 1 below.

TABLE 1 INS PE SE (extraction (precipitate (soluble insoluble) extract)extract) Extraction 85.7% 8.5% 5.8% yield by weight (related to sheabutter) Appearance White solid White solid Yellow liquid CharacteristicsPoor in Enriched in Very enriched unsaponifiables triglycerides inunsaponifiables

EXAMPLE 2 Compared Extractions of Cacao Cake with Hexane andEthoxynonafluorobutane using Soxhlet

This example is designed to provide an element of comparison where itconcerns extraction yields with hexane and the extraction yields withethoxynonafluorobutane.

Cacao cakes (50 g) are extracted using Soxhlet for 5 h with hexane.After extraction, the hexane extract is evaporated and the yield ofextract is calculated based on the weight of the cacao cakes used.

Cacao cakes (50 g) are extracted using Soxhlet for 5 h byethoxynonafluorobutane (C₄F₉—O—C₂H₅). After extraction, the extract iscooled to ambient temperature (20° C.). This operation makes it possibleto decant an insoluble fraction. After removal of the insoluble fractionthe fluorinated supernatant is evaporated. The yields of insolubilisedextract and soluble extract are calculated on the basis of the weight ofthe cakes used.

The compared results of extraction with hexane and, according to theinvention, extraction with ethoxynonafluorobutane, are given in Table 2below.

TABLE 2 Extraction with Extraction with hexane C₄F₉—O—C₂H₅ Yield ofsoluble 3.4% 1.8% extract Yield of extract — 1.6% insolubilised atambient temperature Total yield 3.4% 3.4%

EXAMPLE 3 Extraction of Cacao Cakes with Ethoxynonafluorobutane in 4Successive Extractions

Cacao cakes (500 g) are extracted under shaking at 65° C. for 1 hour 30min by 2 liters (2.86 kg) of ethoxynonafluorobutane (C₄F₉—O—C₂H₅). Thesuspension is rapidly filtered on a filtering screen with 10 μm mesh.The filtrate is cooled to 20° C. in order to precipitate an insoluble asin Example 2. The insoluble is filtered on filtering screen with 10 μmmesh. The intermediate yield in insoluble fraction is calculated on thebasis of the weight of the cakes used. The filtrate obtained is returnedto the extractor for a new extraction cycle using the precedingextraction insoluble. In all, four extraction cycles are carried outaccording to the same operating method. At the end of the last cycle,the final filtrate (separated from the insoluble precipitated at 20° C.)is evaporated under reduced pressure. The yield in soluble materials isexpressed by comparison with the weight of the cakes used. The resultsare provided in Table 3 below.

TABLE 3 Intermediate Cumulative Weight (g) yield yield Extract 1 4.030.81 0.81 insolubilised at 20° C. Extract 2 3.68 0.74 1.55 insolubilisedat 20° C. Extract 3 1.55 0.31 1.86 insolubilised at 20° C. Extract 41.06 0.21 2.07 insolubilised at 20° C. Soluble 3.46 0.69 2.76 materialsn the final filtrate

The extracts insolubilised at 20° C. are yellow in color. The solubleextract is clearer with a strong odor of cocoa.

The qualitative analysis of the fractions is carried out by thin layerchromatography (silica) with the aid of a hexane/ethyl ether/acetic acideluant in proportions by volume of 90/10/1. Deposits correspond to 6 μLof hexane solutions at 20 mg/mL. The plates are dried then visualized byethanol with 5% sulphuric acid (drying at 110° C.). The results showthat the insolubilised extracts are enriched in triglycerides and thatthe soluble materials of the final filtrate are on the other hand,enriched in unsaponifiable materials. In addition, a content of freefatty acids is observed that is much higher in the soluble materials ofthe final filtrate than in the insolubilised extracts.

The examples described above in reference to shea butter and to cacaoillustrate several possibilities of applications of the presentinvention and do not limit the scope of the present invention. In fact,fractionation by the hydrofluoroethers may be applied to numerous otherfatty materials or natural matrixes renowned for their lipid profile aswell as for their uses principally for cosmetic, pharmaceutical or foodpurposes (especially avocado, wheat germ oil, squash and pumpkin seedoil, saw palmetto fruits (Serenoa repens), husks of Pygeum africanum(Prunus africana). The invention may also be applied to animal rawmaterials, to raw materials of animal origin (milk and derivatives, eggproducts, lanolin, beeswax) as well as to unicellular organisms (yeasts,mushrooms, bacteria).

EXAMPLE 4 Fractionation of Shea Butter by Ethoxynonafluorobutane

This example describes the influence of various operating parameters onthe fractionation of shea butter by ethoxynonafluorobutane (HFE7200).These parameters are extraction temperature, retreatment temperature ofthe extract and the number of cycles of extraction carried out on thesame shea butter load.

50 g of shea butter (measuring 6.5% in unsaponifiable) are extractedwith 2 liters of ethoxynonafluorobutane under mild shaking for 30 minand at the extraction temperature T_(E) (50 or 70° C.). Afterdecantation, the biphasic medium is separated into a crude extract (CE1)and a raffinate. The raffinate is subjected two more times to the sameextraction operating method allowing two more crude extracts to beobtained (CE2 and CE3). The three crude extracts (CE1, CE2 and CE3) arestored overnight at a precipitation temperature T_(P) (4° C. or ambienttemperature) in order to cause precipitation of part of thetriglycerides and thus, to increase the content of fluorinated extractsas unsaponifiable. After separation of the precipitates and thesupernatants, then removal of the solvent, 3 precipitated extracts areobtained, respectively, noted PE1, PE2, PE3 and 3 soluble extracts,noted SE1, SE2, SE3.

The indicators making it possible to evaluate the influence of the threeoperating parameters are the weight of the soluble extracts, SE1, SE2and SE3, the unsaponifiable content of the soluble extracts SE1, SE2 andSE3, the extracted unsaponifiable weight present in the extracts SE1,SE2 and SE3 and the weights of the precipitated extracts, PE1, PE2 andPE3.

Table 4 below expresses the influence of these three operatingparameters.

TABLE 4 Precipitation temperature T_(P) (° C.) Ambient Extractiontemperature 4° C. temperature T_(E) (° C.) 50 70 50 70 Weight of SE1 1.50  1.46  0.89  0.89 soluble SE2  1.24  1.23  0.72  0.74 extract (g)SE3  1.09  1.14  0.57  0.58 total  3.83  3.83  2.18  2.21 UnsaponifiableSE1 29.3 31.0 48.2 52.6 content of SE2 19.7 22.9 41.1 42.4 soluble SE317.3 16.6 35.5 35.5 extracts (% w/w) Weight of SE1 440 456 430 470unsaponifiable SE2 244 282 295 314 extracted, SE3 189 189 203 205present in the total 873 927 928 989 soluble extracts (mg) Weight of PE12.10  5.17 2.15  4.72 precipitated PE2 2.18  5.20 2.26  4.62 extract (g)PE3 2.30  5.01 2.19  4.78 total 6.58 15.38 6.60 14.12

The results according to the table indicate that:

The amount of soluble extract depends only on the precipitationtemperature. It increases with T_(P) and decreases with each extractioncycle.

The unsaponifiable content depends only on the precipitationtemperature. It increases when T_(P) decreases and it decreases witheach extraction cycle.

The weight of unsaponifiable extracted remains more or less constant,whatever the extraction and precipitation temperatures. It decreaseswith each extraction cycle.

The amount of precipitated extract depends only on the extractiontemperature. It increases with T_(E) and in addition remains constantwhatever the extraction cycle.

The critical parameter therefore is the precipitation temperature:

for a low precipitation temperature (e.g.: 4° C.) the extraction will beselective (high unsaponifiable content) but less effective (low amountof soluble extract)

for a high precipitation temperature (e.g.: ambient T) the extractionwill be effective (high amount of soluble extract) but not veryselective (average unsaponifiable content)

It will be noted that the most selective extraction (T_(P)=4° C.; 1^(st)extraction cycle) leads to a content of unsaponifiable extract on theorder of 50%. The enrichment factor is on the order of 7.7.

EXAMPLE 5 Fractionation of Shea Butter by Ethoxynonafluorobutane(HFE7200) at 50° C.—Influence of the Precipitation Temperature

Example 4 shows that the extraction temperature has no significantinfluence on the selectivity or efficacy of the extraction. As a resultin this example, the shea butter is treated at an extraction temperatureof 50° C. just higher than its liquefaction temperature.

The operating method of extraction is identical to that of Example 4with the exception of the precipitation temperatures: −18° C., 4° C. andambient temperature.

TABLE 5 Extraction temperature T_(E) (° C.) Precipitation 50 temperatureT_(P) (° C.) Ambient T 4 −18 Weight of SE1  1.50  0.89  0.58 solubleextract SE2  1.24  0.72  0.42 (g) SE3  1.09  0.57  0.31 total  3.83 2.18  1.31 Unsaponifiable SE1 29.3 48.2 70.3 content of SE2 19.7 41.167.4 soluble SE3 17.3 35.5 66.5 extracts (% w/w) Weight of SE1 440 430408 unsaponifiable SE2 244 295 285 extracted SE3 189 203 205 present inthe total 873 928 898 soluble extracts (mg) Weight of PE1 2.10 2.15 2.78precipitated PE2 2.18 2.26 2.85 extract (g) PE3 2.30 2.19 2.86 total6.58 6.60 8.49

The results from Table 5 indicate that:

As in the preceding example, the amount of soluble extract increaseswith T_(P) and decreases with each extraction cycle.

As in the preceding example, the unsaponifiable content increases whenT_(P) decreases and it decreases with each extraction cycle.

As in the preceding example, the weight of unsaponifiable extractedremains more or less constant, whatever the precipitation temperature.It decreases with each extraction cycle.

In contrast to that which the preceding example demonstrates, the amountof precipitated extract becomes dependent on the precipitationtemperature. It increases when T_(P) is low at −18° C. On the otherhand, it remains constant whatever the extraction cycle.

The general conclusions remain unchanged:

for a low precipitation temperature (e.g.: −18° C.) the extraction willbe selective (high unsaponifiable content) but less effective (lowamount of soluble extract)

for a high precipitation temperature (e.g.: ambient T) the extractionwill be effective (high amount of soluble extract) but not veryselective (average amount of unsaponifiable content)

It will be noted that the most selective extraction (T_(P)=−18° C.;1^(st) extraction cycle) leads to a content of unsaponifiable extract onthe order of 70%. The enrichment factor is on the order of 10.7.

What is claimed is:
 1. A method of extraction and fractionation of fattymaterial from a raw material, characterized in that it comprises atleast one extraction step using an extraction solvent formed by at leasta hydrofluoroether with general formula: C_(n)F_(2n+1)OC_(m)H_(2m+1) inwhich n is between 3 and 6 and in is between 1 and 5 and at least oneseparation step leading to obtaining crude extract of fatty materialrich in unsaponifiable substances, and possibly free fatty acids, and aninsoluble extraction fraction.
 2. The method according to claim 1characterized in that said hydrofluoroether is chosen frommethoxynonafluorobutane (C₄F₉—O—CH₃) and ethoxynonafluorobutane(C₄F₉—O—C₂H₅).
 3. The method according to claim 1 characterized in thatit includes a precipitation step selective for triglycerides present insaid crude extract consisting of cooling said crude extract to atemperature lower than the extraction temperature, and filtering saidcrude extract in order to obtain a precipitated extract and a filtrate.4. The method according to claim 3 characterized in that it includesadditional steps of decanting said filtrate then of evaporating it so asto recover a soluble extract.
 5. The method according to claim 1characterized in that the extraction and separation steps areiteratively repeated using said insoluble extraction fraction recycledfrom a prior iteration for the raw material.
 6. The method according toclaim 1 characterized in that it is used in the presence of at least onecosolvent chosen from alkanes, ketones, alcohols, alkyl ethers,carboxylic acids, esters, amides, halogenated hydrocarbons, acetals. 7.The method according to claim 2 characterized in that it includes aprecipitation step selective for triglycerides present in said crudeextract consisting of cooling said crude extract to a temperature lowerthan the extraction temperature, and filtering said crude extract inorder to obtain a precipitated extract and a filtrate.
 8. The methodaccording to claim 7 characterized in that it includes an additionalsteps of decanting said filtrate then of evaporating it so as to recovera soluble extract.
 9. The method according to claim 7 characterized inthat the extraction and separation steps are iteratively repeated usingsaid insoluble extraction fraction recycled from a prior iteration forthe raw material.
 10. The method according to claim 7 characterized inthat it is used in the presence of at least one cosolvent chosen fromalkanes, ketones, alcohols, alkyl ethers, carboxylic acids, esters,amides, halogenated hydrocarbons, acetals.
 11. The method according toclaim 2 characterized in that it is used in the presence of at least onecosolvent chosen from alkanes, ketones, alcohols, alkyl ethers,carboxylic acids, esters, amides, halogenated hydrocarbons, acetals. 12.The method according to claim 2 characterized in that the extraction andseparation steps are iteratively repeated using said insolubleextraction fraction recycled from a prior iteration for the rawmaterial.
 13. The method according to claim 12 characterized in that itis used in the presence of at least one cosolvent chosen from alkanes,ketones, alcohols, alkyl ethers, carboxylic acids, esters, amides,halogenated hydrocarbons, acetals.
 14. The method according to claim 3characterized in that it is used in the presence of at least onecosolvent chosen from alkanes, ketones, alcohols, alkyl ethers,carboxylic acids, esters, amides, halogenated hydrocarbons, acetals. 15.The method according to claim 3 characterized in that the extraction andseparation stews are iteratively repeated using said insolubleextraction fraction recycled from a prior iteration for the rawmaterial.
 16. The method according to claim 15 characterized in that itis used in the presence of at least one cosolvent chosen from alkanes,ketones, alcohols, alkyl ethers, carboxylic acids, esters, amides,halogenated hydrocarbons, acetals.
 17. The method according to claim 4characterized in that it is used in the presence of at least onecosolvent chosen from alkanes, ketones, alcohols, alkyl ethers,carboxylic acids, esters, amides, halogenated hydrocarbons, acetals. 18.The method according to claim 4 characterized in that the extraction andseparation steps are iteratively repeated using said insolubleextraction fraction recycled from a prior iteration for the rawmaterial.
 19. The method according to claim 12 characterized in that itis used in the presence of at least one cosolvent chosen from alkanes,ketones, alcohols, alkyl ethers, carboxylic acids, esters, amides,halogenated hydrocarbons, acetals.
 20. The method according to claim 5characterized in that it is used in the presence of at least onecosolvent chosen from alkanes, ketones, alcohols, alkyl ethers,carboxylic acids, esters, amides, halogenated hydrocarbons, acetals.